No group, including ISIS, has yet claimed responsibility for the explosion that rocked Manchester Arena, but UK police are treating it as a terrorist incident until proved otherwise.

Today, in the wake of chaotic and bloody scenes in Manchester, ISIS Twitter accounts were jubilant.

"Kill him everywhere," was emblazoned across one graphic showing a heavily armed jihadi soldier watching a building burn.

A pro-ISIS Twitter account celebrates the suspected terror attack on Manchester. Nine.com.au viewed several accounts promoting ISIL propaganda, which have since been shut down by Twitter. Source: Twitter ()

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Another image showed clock tower Big Ben smouldering with smoke, while other violent graphics targeting westerners were hashtagged with #ArianaGrande and #ManchesterArena.

Pro-ISIS Twitter accounts have recently called on supporters to "hunt your prey" in the US, UK and Europe, according to SITE Intelligence Group, a non-governmental counter-terrorism organisation.

Counter-terror analyst Rita Katz said on Twitter that she had observed ISIS pushing out detailed information on community centres, tourist areas and government buildings in various cities.

Scores of people were injured by a suspected suicide bomber and crowds rushing to escape Manchester Arena. At least 19 people have been killed by a probable suicide bomber who attacked the Ariana Grande concert in Manchester. Credit: Joel Goodman/LNP ()Police deploy at scene of explosion in Manchester, England. Source: AFP ()

In November last year, ISIS officially released detailed instructions on how to make a home-made bomb, Katz added.

Nine.com.au checked several of the pro-ISIS Twitter accounts flagged by Katz and SITE Intelligence Group, but the social media company had already shut down the offending users.

It appears that the Ariana Grande explosion, which is feared to be the work of a suicide bomber, will be the worst terrorist attack in the UK since the London attacks in 2005.

At least 19 people have been killed by a probable suicide bomber who attacked the Ariana Grande concert in Manchester. Credit: Joel Goodman/LNP ()

That co-ordinated bombing attack on London's public transport system was carried out by four radicalised young men, and killed 52.

Pop star Ariana Grande, who was unhurt in Tuesday's incident (AEDT), has a largely young and female following.

Prime Minister Theresa May, in the midst of an election campaign, said it appeared to be an "appalling attack".

Hamza bin Laden, pictured with dead father Osama, pre 9/11, is believed to have been groomed to take a leadership role with al Qaeda. Source: 60 Minutes ()

Just last week, terror group al Qaeda released a 10-minute audio tape where Hamza bin Laden, son of Osama, called on its followers to launch lone wolf style attacks on western targets and citizens.

Counter-terror intelligence experts have expressed concerns that as ISIS' self-proclaimed caliphate is beaten back in Iraq and Syria that lone wolf attacks will rise in the west.